Joint replacement procedures are used to repair damaged joints. During a joint replacement procedure the joint is preferably aligned, bone or bones of the joint may be resected, and a prosthesis may be implanted on the resected bone. Joint replacement procedures may be performed on the knee, hip, shoulder or elbow joints, for example. Accuracy of joint alignment and bone resection is crucial in a joint replacement procedure. A small misalignment may result in soft tissue or ligament imbalance and consequent failure of the joint replacement procedure. Provision of patient specific or customized cutting guides and prostheses has been used to attempt to improve the outcome of joint replacement procedures.
Preoperative planning is used to prepare a surgical plan based on the scan data or to determine what instruments or prosthetic components should be used to achieve a desired surgical result. Preoperative planning is also used to design such patient-specific guides and prostheses for use in joint replacement procedures. Prior to the surgical procedure, scan data associated with a joint of the patient is generally obtained, a three-dimensional model of the joint based on the scan data is prepared, and guides and/or prostheses based on the model are designed. Once the guides and/or prostheses are designed, information regarding manufacture of these components may be sent to additive manufacturing equipment for manufacture, for example.
Patient-specific guides generally include an inner guide surface designed to mate with a joint surface of the patient such that the guide and joint surface are in a nesting relationship to one another. Accordingly, such guides may mate or “lock” onto the articular surface of the joint in a unique position determined in a final surgical plan. Apertures in the guide are generally designed to locate a guide member or guide a resection device. The guides are preferably designed with such apertures in a preoperatively planned position in order to achieve a desired bone resection such that a prosthesis can be placed in a desired position and orientation.
In tradition and reverse shoulder arthroplasty procedures it is important to accurately locate a prosthesis for attachment to the scapula. In these procedures, fixation screws are used to secure a glenoid cup or baseplate for glenosphere, for example, to the scapula. In order for the cup or baseplate to be sufficiently secured to endure loads during physical therapy and use post surgery, the fixation screws generally need to be fixated to healthy bone stock. There exists a need for locating these prostheses along with fixation screws thereof in a preoperatively planned position and orientation with respect to the native bone stock.